public class Main {

    public static void main(String[] args) {
        Object locker = new Object();
        Thread t1 = new Thread(()->{
            synchronized (locker) {
                System.out.println("t1 wait 之前");
                try {
                    locker.wait();
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                }
                System.out.println("t1 wait 之后");
            }
        });
        Thread t2 = new Thread(()-> {
            try {
                Thread.sleep(3000);
                synchronized (locker) {
                    System.out.println("t2 notify 之前");
                    locker.notify();
                    System.out.println("t2 notify 之后");
                }


            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
        });

        t1.start();
        t2.start();
    }
}
